JPH01158327A - Load gage - Google Patents

Abstract

PURPOSE:To implement a low cost, a compact configuration and a light weight, by arranging three or more elastic beams between two sheets of flanges in a geometrical pattern, and providing strain detecting means at the central part and one end part of a semicircular elastic part of each elastic beam. CONSTITUTION:An elastic beam 1 is constituted with a semicircular elastic part 1a and fixing parts 1b-1c for upper and lower flanges 9 and 10, which are provided at both ends of the elastic parts, in a vertical symmetry pattern. Strain detecting means 11a, 11b, 12a and 12b are attached to the front and rear surfaces of the center of the elastic part 1a and the front and rear surfaces of one end part of the elastic part 1a. The elastic beams 1-3, which are constituted in this way, are arranged between the flanges 9 and 10 so that an equilateral triangle is formed with central axes C1-C3. The fixing parts 1b-3b are connected to a lower surface 9b of the flange 9. The fixing parts 1c-3c are connected to a top surface 10a of the flange 10. Since the force acting between the flanges 9 and 10 is transmitted to the beams 1-3, each acting force can be detected by detecting the deformed amounts of the beams 1-3 with the strain detecting means.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a load needle used to measure forces acting on a rigid body such as a robot hand or a machine tool tool, and more specifically relates to a load needle used for measuring forces acting on a rigid body such as a robot hand or a machine tool tool. The present invention relates to a six-axis force sensor that can detect force by decomposing it into a force in the direction of a reference coordinate axis and a moment around the coordinate axis.

<Prior art> For example, in an assembly operation in which a bottle of an assembly robot is inserted into a hole, the robot hand is A load cell is used to detect the force acting on the

Regarding this type of load cell, conventionally, for example, Japanese Patent Application Laid-Open No. 60-6
Some of them are disclosed in Japanese Patent No. 2497. This method uses a radial plate structure and a reference for this radial plate structure in a multiaxial force sensor coupled between a first rigid body and a second rigid body to detect a load transmitted between these two rigid bodies. This is a multi-axial force sensor characterized by having a radial plate structure and a parallel plate structure (one of which is integrally constructed) with an axis that is neither coincident nor parallel to the axis as a reference axis.

<Problems to be Solved by the Invention> However, the technique disclosed in JP-A-60-62497 has a complicated structure and requires a large number of strain gauges, so machining costs are high. Material costs, labor costs, etc. are high, resulting in an expensive product, and since the strain detection part has a triple structure in the radial direction, the outer diameter is large and the weight is also heavy. However, it has the disadvantage that it cannot be made small and lightweight, which is necessary for equipping it to a robot hand.

In particular, the high price of the product is one of the major factors that hinders the spread of intelligent robots.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a load cell that is inexpensive to manufacture, is small and lightweight, and is suitable for widespread use of intelligent robots.

Means for Solving the Problems> A first aspect of the present invention provides a load cell that is connected between two rigid bodies that are objects to be measured and that detects the force acting on these rigid bodies. and a load cell, and at least three elastic beams arranged in a delta or star shape between these two flanges, and these elastic beams form a semicircular arc shape. It is formed of an elastic part and a fixing part that is fixed to both ends of these elastic parts and can be connected to the flanges, respectively, and strain detection means are provided at the elastic part, the center part, and one end, respectively. A second aspect of the present invention is a load cell configured to provide a load cell that is connected between two rigid bodies that are objects to be measured, and that detects the force acting on these rigid bodies. The meter is composed of two flanges connecting the two rigid bodies and the load cell, and at least four elastic beams arranged in a square shape or radially between these two flanges, and these elastic beams is formed of an elastic part having a semicircular arc shape, and a fixed part fixed to both ends of these elastic parts so as to be connectable to each of the flanges, and the elastic part, a central part, and one end are connected to each other. This load cell is characterized in that it is configured such that strain detection means are provided in each of the two.

The elastic beam includes an elastic part having a semicircular arc shape, parallel parts having equal lengths extending parallel to both ends of the elastic part, and fixedly attached to both ends of these parallel parts, each connected to the flanges. It may be formed into a U-shape with a possible fixing part, or it may be formed into a U-shape in which the elastic part forms a vertical straight line.

<Operation> According to the present invention, at least three semicircular arc-shaped, U-shaped, or U-shaped elastic beams are arranged between two flanges in a delta shape or star shape, or at least four of the elastic beams are arranged in a delta shape or a star shape between two flanges. Since the sensor is arranged in a rectangular or radial manner to form a 6-axis sensor, it can be made smaller and lighter.

<Example> Below, an example of the present invention will be described in detail based on the drawings.

[Example 1] First, the first aspect of the present invention will be explained.

FIG. 1 is a side view showing one embodiment of an elastic beam used in a load cell according to the present invention. Since three elastic beams are required in this embodiment, the related symbols are corresponding in the figure. Also listed.

In the figure, the elastic beam 1 first has an elastic part 1a having a semicircular arc shape with a radius R, and a fixing part 1b with upper and lower flanges provided at both ends of the elastic part 1a.

1c, and a strain detecting means 11a is provided on the front and/or back surface of the center of the elastic portion 1a.

11b also covers the surface of one end of the elastic portion 1a and/or
Alternatively, strain detection means 12a and 12b are attached to the back surface.

Similarly, the elastic beam 2 has an elastic part 2a and a fixed part 2b.

2c, and strain detection means 13a, 13b and 14a, 14b are attached to the center and one end of the elastic portion 2a. Similarly, the elastic beam 3 is composed of an elastic section 3a and fixed sections 3b and 3c, and the elastic section 3a is provided with strain detection means 15a, 15b and 16a.

16b is attached.

Using the three elastic beams 1.2°3 thus constructed, the load cell of the present invention is assembled as shown in FIGS. 2 and 3.

FIG. 2 is a plan view showing an embodiment of the load cell according to the present invention, and FIG. 3 is a side view thereof.

In these figures, 9 is the upper flange and 10 is the lower flange. Here, for example, when the load cell of the present invention is used in a robot, the upper surface 9a of the upper flange 9 is fixed to one rigid body (not shown), such as a robot hand, and the lower surface 10b of the lower flange 10 is fixed to the other rigid body (not shown). fixed to a rigid body, such as a robot arm. Between the upper flange 9 and the lower flange lO, the three vertically symmetrical elastic beams 1, 2.3 are arranged so that they form a delta shape with their respective central axes c, C2+C2, that is, their respective The fixed portions lb of each elastic beam 1.2.3 are uniformly arranged so as to form an equilateral triangle shape whose central axes intersect at an angle of 60' in the flange plane.
2b, 3b are the lower surface 1b of the upper flange 1, and the other fixed portions 1c, 2c, 3c are the upper surface 2 of the lower flange 2.
a and are respectively joined.

Note that if the strain detection means are attached to the front and back surfaces of the elastic beam, the detection sensitivity can be doubled.

Further, although a preferred embodiment is shown in which each elastic beam is formed into an equilateral triangular shape with an intersection angle of 60", the present invention is not limited to this, and may be formed into an isosceles triangular shape or a simple triangular shape. It doesn't matter if it's a shape.

By configuring the load cell in this way, the force acting on the robot hand, for example, is transmitted from the upper flange 9 to the elastic beams 1, 2, and 3 to the lower flange lO to the robot arm, thereby reducing the deformation of the elastic beam. The amount can be detected by strain detection means.

Hereinafter, a method for detecting strain will be explained using a case where a strain gauge is used as a strain detecting means as an example.

Now, if the amount of strain obtained from each strain gauge 11.12.13.14.15.16 of elastic beam 1, 2.3 is C3, C2, C1, C4, C3, C6, then each amount of strain is Force FX in the X-axis direction, force F in the y-axis direction,
Force in two axial directions F*s Moment M around the X-axis.

Since it represents the magnitude when six-axis forces such as moment M around the y-axis and moment M around the z-axis are applied, there is a relationship as shown in the following equation.

−・−−−−−−−−−−−−−−−−−−−−−−
-------・---・-- (1) Here, k is a constant.

If we use this equation (1) to measure ε, the acting force will be F,,FV,F,,M,,M,.

By decomposing each into M2 and detecting them, C1 is obtained.

In this example, three elastic beams 1.2.
3 are arranged in a delta shape, but the present invention is not limited to this arrangement, and the same effect can be achieved even if they are arranged in a star shape as shown in FIG. In this case each elastic beam 1
．． Preferably, the intersection angles of the central axes Ct, Cz, and Cs of 2.3 are all 120''.

However, this intersection angle is not limited to 120 degrees, but may be any angle within the range of 60' to 150 degrees.

Furthermore, the number of elastic beams is not limited to three;
As shown in a), each central axis CII C! + It is also possible to install two pieces symmetrically on the left and right sides of C2, and configure it with six pieces as shown in FIGS. 5(b) and (C).

The shape of the elastic beam is U, with a parallel part rd provided between the elastic part fa and the fixed parts fb and fcO, as shown in FIG.
If a letter-shaped elastic beam beam is used and the strain detection means 12a, 12b are attached to one surface and/or the back surface of the parallel portion 1d, the sensitivity can be doubled. Note that in this case, three elastic beams are sufficient.

The shape of this elastic beam also has a vertical length as shown in Figure 7! , and a horizontal length j2.
It is also possible to form the elastic beam 11 into a U-shape formed by the parallel portion I'd.

[Example 2] Next, a second aspect of the present invention will be described using FIG. 8 and FIG. 9.

As shown in FIG. 8(a), the respective central axes C+, CtlCs, and C4 of the four vertically symmetrical elastic beams 1, 2, and 3.4 between the upper and lower flanges 9 and 10 are square or square within the flange plane. Arrange them to form a rectangular shape.

With this configuration, elastic beams 1.2.
3.4 The amount of strain obtained from the strain gauges attached to the center and ends of each can be detected for each acting force from the relationship of equation (1) above.

In addition, as shown in FIG. 8(b), each central axis C,,C2
It is also possible to arrange two elastic beams symmetrically on C3 and Cm to form eight elastic beams 1.5.2, 6.3.7.4.8.

In addition, as shown in Figure 8(C), 4
A similar effect can be obtained by arranging several elastic beams 1, 2, 3.4. - Furthermore, the same effect can be obtained even if the four elastic beams 1, 2, 3.4 are arranged radially as shown in FIG. Here, the intersection angles of each central axis C+, Ct, Cs, Ca of the elastic beam 1°2.3.4 with the y axis are all the same angle, such as θ, and the central axis C
I and C2 and C3 and C4 are arranged to intersect, for example, at a distance of a from the intersection of the y-axis and the y-axis on the X-axis.

The magnitude of the intersection angle θ needs to be regulated in order to accurately detect the y-axis and the forces F, , F acting on the y-axis, and is preferably 45°, for example. In addition, the size of the intersection Ha needs to be regulated in order to accurately detect the moment (Mz) acting around the two axes, and the elastic beams 1, 2.3
．． 4 and the size of the flange 9.10.

Note that the crossing angle θ and the crossing distance a may be given with respect to the y-axis.

Further, it goes without saying that even if the shape of the elastic beam used in the above embodiment is U-shaped or U-shaped as in the first embodiment, the same effect can be achieved.

<Effects of the Invention> As explained above, according to the present invention, since an elastic beam having a semicircular arc shape, a U shape, or a U shape is used, the load cell can be made smaller and lighter. It can contribute to the spread of intelligent robots because it has a power of 5 and can be manufactured at low cost.

[Brief explanation of the drawing]

FIG. 1 is a side view showing an embodiment of a semicircular arc-shaped elastic beam used in a load cell according to the present invention, and FIG. 2 is a plan view showing an embodiment of a load cell in which semicircular arc elastic beams are arranged in a delta shape. Fig. 3 is a side view of Fig. 2, Fig. 4 is a plan view showing an example of a load cell in which semicircular arc elastic beams are arranged in a star shape, and Fig. 5 is a semicircular arc elastic beam. 6 is a side view showing another embodiment of the U-shaped elastic beam, and FIG. 7 is a side view of the U-shaped elastic beam. FIG. 8 is a side view showing an embodiment of the load cell; FIG. 8 is a plan view showing an embodiment of a load cell in which semicircular arc elastic beams are arranged in a rectangular manner; FIG. 9 is an example of a load cell in which semicircular arc elastic beams are arranged radially. FIG. 1.2, 3.4, 5.6, 7.8...elastic beam, 9
... Upper flange, 10 ... Lower flange, 1
1.12, 13, 14, 15.16...distortion detection section. Patent Applicant Kawasaki Steel Corporation Figure 1 Figure 2 ■ Figure 3 Figure 4 ■ Figure 5 (a) (b) Figure 5 (C) Figure 6 Figure 8 (a) (C) Figure 9 figure

Claims (4)

[Claims] (1) In a load cell that is connected between two rigid bodies that are objects to be measured and that detects the force acting on these rigid bodies, there are two flanges that connect the two rigid bodies and the load cell, and two flanges that connect the two rigid bodies and the load cell. at least three elastic beams arranged in a delta or star shape between the flanges of the
These elastic beams are formed of elastic parts having a semicircular arc shape, and fixing parts fixed to both ends of these elastic parts so as to be connectable to the flanges, respectively, and between the elastic part, the center part, and one of the elastic parts. A load cell characterized in that a strain detection means is provided at each end. (2) In a load cell that is connected between two rigid bodies that are objects to be measured and that detects the force acting on these rigid bodies, two flanges that connect the two rigid bodies and the load cell, and two flanges that connect the two rigid bodies and the load cell. At least four elastic beams are arranged in a square shape or radially between the flanges of the flange, and these elastic beams include an elastic part having a semicircular arc shape, and fixedly attached to both ends of these elastic parts. and a fixing part which can be connected to each other, and strain detecting means are provided in each of the elastic part, the center part, and one end part. (3) The elastic beam includes an elastic part having a semicircular arc shape, parallel parts extending parallel to both ends of the elastic part and having equal lengths, fixed to both ends of these parallel parts, and connected to the flange, respectively. Claim 1 or 2, characterized in that it is formed in a U-shape with a fixing part that can be connected.
Load cell described in section. (4) The load cell according to claim 1 or 2, wherein the elastic beam is formed in a U-shape with an elastic portion forming a vertical straight line.